Rock 'n' roll was all about revolution. You grew your hair, squeezed into drainpipe trousers and aimed your Fender at the squares, as they lamely kow-towed to 'the man'. For the rock 'n' rollers, the art came first, which meant keeping quiet about the cash. Too much moolah could damage your credibility.
But in recent years, rap stars have, in the genre's unique parlance, 'bum-rushed the show', changing the rules and turning the traditional music model on its head. While rich rockers had to pretend they were still just like the rest of us, rappers have gone the other way. Lyrics are shamelessly consumerist; the artists have become chief execs chasing expansion into fresh markets; and songs even directly advertise their products. It's all about the Benjamins (Franklin, on the $100 note and the half-dollar coin).
And these rappers are beating the establishment at its own game. They may well have proved smarter than the record execs, finding fresh ways to thrive as the industry shatters its hips in an arthritic collapse. While their rock and pop counterparts are reeling from a drop in CD sales, rappers seem more concerned with their investment portfolio. Instead of tuning in and dropping out, they broke in and bought the building. But will their paying public tire of such flagrant excess?
Rapper Sean John Combs, aka P Diddy, earned $35m last year. As well as running Bad Boy records, he also owns a sportswear label, Sean John. On its website, you can watch him swagger out of the shower in a towel, while a doting valet slips a rock onto his finger. In 2008, the rapper even fronted his own version of The Apprentice, VH1's I Want to Work for Diddy. Episodes have such titles as 'No Bitchassness Allowed'. It's Sir Alan Sugar, the Bad Boy remix.
He may like to play the business big shot, but Diddy isn't the real daddy. That honour falls to 50 Cent (aka Fiddy), born Curtis James Jackson III. He earned $100m after tax last year at a single stroke, when Coca-Cola paid $4.1bn for VitaminWater-maker Glaceau. Cent had shrewdly taken a stake in the company as payment for endorsing the brand. If you're surprised by the figures, so was he - at least, if his lyrics to I Get Money are anything to go by: 'I took quarter water, sold it in bottles for two bucks, And Coca-Cola came and bought it for billions, what the fuck?'
When, in 2003, Cent released his debut album Get Rich Or Die Tryin', he also launched a fashion brand, G-Unit. Two years later came his second album (The Massacre) and the video game, the book, the film and the vitamin water. Cent also has a body-spray label, a clothing range with tie-ups with Reebok, and his own line in condoms: MagicStick (with, of course, an X-rated song of the same name). He's now rumoured to be investing in a South African platinum mine. Not bad for a former cocaine dealer who's been shot nine times.
This man knows what he wants, and knows how to get it. 'He may sell nine million copies,' says hip-hop historian Jeff Chang, 'but he realises the real thing is to leverage yourself across synergised platforms and consolidate. He's aptly named - trying to make a dollar out of 50 cents.'
He's not the only one. Back in the mid-90s, New York hip-hop group Wu-Tang Clan raised the stakes with its urban clothing brand Wu-Wear. When the band was commissioned to perform a song for a movie, it penned Garment Renaissance, urging impressionable fans to quit buying Benetton and Liz Claiborne and blow their cash on Wu products instead. 'Wu-Tang Clan would have been paid a fee to contribute to the soundtrack, as well as a fee every time it's played,' says rap critic Angus Batey. 'It took that fee and gave itself an advert. It's remarkable.'
So how could the likes of Wu, Fiddy and Diddy get away with such cynical commoditising of their art? It would be impossible, for example, to imagine the grunge world going wild for Nirvana trainers, despite the band's huge global following. And if Kurt Cobain had tried anything so blatantly commercial, the unwashed hordes wouldn't have worn it.
But while grunge came from suburban white kids looking to drop out, urban rap music is driven by the opposite: the desire to buy into the American dream, and to be recognised. 'Someone who writes a painfully honest song about the break-up of their relationship is thinking more about creating the perfect piece of art,' says Batey, 'rather than what that music gives them in terms of expanding their profile. Rap is an extrovert, brag-fuelled genre; the rappers have always been entrepreneurial and can be a lot more upfront about it.' And more honest too.
For the classic rap entrepreneur's tale, look no further than Jay-Z (ne Shawn Corey Carter). He went from hustling drugs on the street to setting up his own label, Roc-A-Fella, and a clothing brand, Rocawear. The former recorded sales of $90m in the first year. He sold Roc-A-Fella to Universal in 2004, and later became the chief exec and president of iconic label Island-Def Jam. 'I don't have a template on how to be a (chief executive),' he told the BBC. 'I'm still myself. I'm still a straight shooter.' This approach earned him $82m last year.
Like 50 Cent, Jay-Z must be credited with spotting a profound shift in the entertainment industry, and making deliberate moves to exploit it, rather than sitting there and being told what to do. He saw early that being a musician is no longer just a matter of forming a band and spending your life pretending to be Keith Richards. Things have moved on.
In April last year, Jay-Z signed a 10-year, $150m deal with concert promoter Live Nation. It's a similar set-up to Madonna's. Her deal got a lot of press at the time as an alternative to the traditional label set-up (it was worth $120m to Madge). It recognises that an artist's main income no longer comes from record sales; it's now about everything from touring to hosting your own TV show. Jay-Z's staggering deal includes an upfront payment of $25m, plus $50m to finance his own outside interests.
As well as part-owning the New Jersey Nets basketball team and a swanky club chain, 40/40, Jay-Z has a deep understanding of his most important brand: Jay-Z. Take 2007's comeback album, American Gangster, which was accompanied by seemingly unlikely tie-ups with Hewlett-Packard and Budweiser, as well as US sports brands Nascar and NFL. 'He takes care of all income classes, all lifestyle markets,' says Chang. 'He's on the cover of Esquire and hanging out with Coldplay's Chris Martin and his wife Gwyneth Paltrow. And the record sells 800,000 in the first week, a phenomenal amount. And he hasn't signed his life away - he is, of course, the president of the record company.'
'It's about understanding the core of your identity and recreating that across lots of spaces,' adds Chang. 'He's close to the ground and agile, like Barack Obama: all things to all people simultaneously.'
It's 30 years since the release of Rapper's Delight, the 12-inch single by the Sugarhill Gang that brought rap international attention. The band had been cobbled together by producer Sylvia Robinson and her husband, label exec Joe Robinson, who, eager to make a quick buck out of the burgeoning underground culture, drove from New Jersey to the Bronx to scout for kids to record. He auditioned the members in his car.
The conspicuous consumption was all there. Take Sugarhill Gang rapper Henry Jackson, aka Big Bank Hank: 'I got two big cars that definitely ain't the wack, I got a Lincoln Continental and a sunroof Cadillac...' Only one small caveat: Hank may have claimed Big Bank, but he actually worked in a pizza shop. 'At that time it was cute,' says Chang. 'These were tall tales. Obviously, after school you didn't take a dip in the pool - you took the train to go and work. They're aspirational fantasies, a line in the raps that goes all the way back.'
Today's fans express that aspiration by buying rappers' products. Even their eagerness to own 50 Cent's G6 Reeboks has its precedent. In Naomi Klein's book No Logo, she tells how Russell Simmons took Adidas executives to a 1987 show by Run DMC in a bid to get sponsorship. They were suitably sceptical. That changed when the band performed its ode to its favourite trainer, My Adidas, and the crowd held thousands of the shoes in the air. Last year, USA Today ranked Simmons the 23rd most important person in the world. That's one spot below the Clintons.
By the early '90s, the majors had begun paying attention to what the kids on the street were listening to. They could then package it, and sell it back to them. When sales-tracking service SoundScan was launched in 1991, it found the top-selling records across the US were country music singer-songwriter Garth Brooks and gangster rappers NWA (Niggaz with Attitude). MTV was soon playing rap on repeat, and McDonald's began offering $2 to rappers for every mention of the Big Mac in their lyrics. In a 1999 cover story, Time magazine reported that, with 81 million CDs sold, rap was officially America's top-selling genre.
The lesson in commercial takeover isn't lost on today's rap entrepreneurs. As Chang puts it: 'A principle driving Jay-Z's ambition, to become CEO of Def Jam or run a multimillion dollar fashion company, comes from the very fresh memory of what it's like to be completely exploited.'
Those days of exploitation are long gone. Rappers are now the ones kicking back in the swivel chairs. To any rockers still convinced of the superiority of the old model, last summer's Glastonbury festival may serve as a warning: the headline slot went to Jay-Z. 'I'm not having hip-hop at Glastonbury,' said Oasis' Noel Gallagher. 'It's wrong.' Jay-Z didn't care: he stormed on stage clutching a guitar, duly murdered the Oasis signature Wonderwall, then burst into his own hit, I got 99 Problems (But a Bitch Ain't One). Glastonbury was his.
But how long the rap takeover will last is hard to tell. SoundScan reported hip-hop sales dropping a stark 45% between 2000 and 2006. The likes of 50 Cent may need to work on their offering. First, there's the moral question: people can surely listen only so much to boasts about material wealth, especially when they come through songs blatantly peppered with plugs for your own business interests. But beyond the moral issue, there's something more practical at play: a tough economy may drive people to seek something more wholesome.
Yet rappers clearly have the nose for changing trends, and if any areas of the record industry look agile enough to survive the current crisis, it'll be the more inherently entrepreneurial genres such as rap.
Jay-Z probably won't pay too much heed. When not planning his next move, he's too busy enjoying himself. 'That bloke from Oasis said I couldn't play guitar,' he raps. 'Someone should have told him I'm a fuckin' rock star.'
RAP'S BUSINESS BIBLE: THE 48 LAWS OF POWER
Rappers don't seem the type for self-help books. They tend to ascribe their success to their experience hustling drugs or home-produced tapes, rather than the woolly pronouncements of books like Rhonda Byrne's The Secret. It's hard to picture 50 Cent sitting on a bean-bag wishing so hard that all his dreams eventually come true.
But there's one book that has had every self-respecting rap mogul scurrying to the mind-body-spirit shelves: Robert Greene's 1998 tome, The 48 Laws of Power, a work that condenses historical wisdom from the likes of Machiavelli into a practical handbook of ladder-climbing.
It's a brutal read: Law 11, 'Learn to keep people dependent on you'; Law 14, 'Pose as a friend, work as a spy'; Law 27, 'Play on people's need to believe to create a cultlike following'. Shudder at the macho lack of compassion but the music business is famously ruthless.
Greene is co-writing an updated version with 50 Cent, called The 50th Law, an 'urban' version of the book that identifies Fiddy's 'laws of hustling'. 'There are 10 of them,' Greene has said, 'but they have no connection to the 10 Commandments or anything.' Good to see there's modesty among all the manipulation.
Jay-Z, 50 Cent and P Diddy use their street swagger to push brands, including Fiddy's G Unit trainers. No smiles allowed.